No, it's not better because the top class is never cheap. That's the way of thinking which has been again and again proven wrong. The top level is always expensive from the principle - even if it's wooden bikes it's expensive when you develop the best in the world. Making R5 the top class would only make R5 more expensive not the WRC reasonably cheaper.

Simply don't repair what is not broken. For God's sake when we finally have something which works give it time and don't change it again. R5 do work and they work very well. In fact there is no other similarly successful concept in the rallying (except maybe S2000 if they were not killed at their popularity peak by the change of the rules).